JPH0761191B2 - Deep bass playback device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a deep bass reproducing apparatus suitable for use in, for example, a radio cassette tape record, a television receiver, and the like.

[Prior Art] FIG. 6 is a block diagram showing a configuration of an example of a conventional deep bass reproducing apparatus disclosed in Japanese Patent Laid-Open No. 1-149696.

The audio signal reproduced and output from the reproducing apparatus 1 is input to the amplifier 6 via the adder 2 and amplified, and then the speaker 7
It is supposed to be emitted more.

A part of the audio signal output from the reproducing apparatus 1 is input to the low pass filter (LPF) 4 and its low frequency component is extracted. The extracted low frequency component is input to the pitch conversion circuit 5,
It is converted into a signal with a lower pitch (a signal with a lower frequency). The output of the low pass filter 4 and the output of the pitch conversion circuit 5 are input to the adder 3 and added. The output of the adder 3 is further input to the adder 2 and added with the signal from the reproducing device 1.

This makes it possible to reproduce deep bass even if the audio signal has relatively low low-frequency components (for example, frequency components of 80 Hz or less), as in the case of television broadcasting, for example.

[Problems to be Solved by the Invention] In order to enhance the effect of heavy bass reproduction, it is necessary to set the cutoff frequency of the low-pass filter 4 to a frequency that is somewhat high. However, if the cutoff frequency is set too high, the human voice, especially the male voice, becomes unnatural. Therefore, the conventional device has a problem that the cut-off frequency cannot be set too high, and eventually the deep bass effect cannot be sufficiently exerted.

Further, in the pitch converting circuit 5, the amplifier 6 and the speaker 7
When an audio signal that exceeds the frequency characteristics of
Unnecessary vibration was given to the speaker 7 and distortion was generated, so that effective deep bass reproduction could not be performed.

The present invention has been made in view of such a situation, and makes it possible to effectively reproduce deep bass without making the human voice unnatural.

[Means for Solving the Problem] The heavy bass reproducing apparatus according to claim 1,
A first low-pass filter (for example, the low-pass filter 4 in FIG. 1) that separates low-frequency components of approximately 150 Hz or less, and a pitch conversion circuit that converts the output of the first low-pass filter into a signal having a frequency of approximately 1/2. (For example, the pitch conversion circuit 5 in FIG. 1)
And an adder (for example, the adder 3 in FIG. 1) that adds the output of the first low-pass filter and the output of the pitch conversion circuit,
The second that separates low frequency components below approximately 80Hz from the input signal
Low-pass filter (for example, the low-pass filter of FIG. 1)
11) and a control circuit (for example, the voltage control amplifier 14 in FIG. 1) that controls the addition ratio of the output of the pitch conversion circuit to the output of the first low-pass filter corresponding to the output of the second low-pass filter. It is characterized by being provided.

[Operation] In the heavy bass reproduction device according to the first aspect, the ratio of the signals generated and added by the pitch conversion circuit is controlled in accordance with the frequency of the input signal. For example, if there are many low-frequency components (components of 80 Hz or less) lower than that of a human voice, particularly a male voice, it is determined that the input is not a human voice but a musical sound, and the bass is emphasized. If the low-frequency component is small, it is determined to be a human voice, and the bass is not emphasized. Therefore, it is possible to prevent the human voice, particularly the male voice, from becoming unnatural.

[Embodiment] FIG. 1 is a block diagram showing the configuration of an embodiment of the heavy bass reproducing apparatus of the present invention. The parts corresponding to those in FIG. Therefore, the description thereof will be omitted as appropriate.

In the heavy bass reproducing apparatus of the present invention, the signal output from the reproducing apparatus 1 is input to the low-pass filter 11, the output is amplified by the amplifier 12, and then supplied to the DC conversion circuit 13. . The output of the DC conversion circuit 13 is input to a voltage controlled amplifier (VCA) 14 (control circuit). The voltage control amplifier 14 adjusts the output of the pitch converting circuit 5 to a level corresponding to the output of the DC converting circuit 13 and outputs the adjusted output to the adder 3.

Other configurations are the same as those in FIG.

In the above embodiment, when the cutoff frequency of the lowpass filter 4 is set to, for example, 150 Hz, the cutoff frequency of the lowpass filter 11 is set to, for example, 80 Hz. Since the low-pass filter 11 needs to have a sharp cutoff characteristic, for example, a Chebyshev circuit of the third order or higher can be used. It is preferable that the low-pass filter 4 also has a third-order or higher structure.

The pitch conversion circuit 5 converts a frequency of 150 Hz or less into, for example, a half frequency (75 Hz or less) and outputs the frequency to the voltage controlled amplifier 14.

The low pass filter 11 extracts a signal having a frequency of 80 Hz or less. This low-frequency component is amplified by the amplifier 12 and then input to the DC conversion circuit 13 and converted into a DC voltage. The output of the DC conversion circuit 13 is supplied to the voltage controlled amplifier 14 as a control voltage.

When the audio signal output from the reproducing apparatus 1 is mainly human voice, the frequency of the main energy component is higher than 80 Hz, so the low-pass filter 11, and hence the DC conversion circuit 13 is used.
Output is smaller. As a result, the voltage controlled amplifier 14
The output level of the pitch conversion circuit 5 is reduced and output to the adder 3. That is, at this time, the bass is not emphasized so much that the human voice is prevented from becoming unnatural.

On the other hand, when the audio signal output from the reproducing device 1 is a musical sound signal, the frequency component of 80 Hz or less is larger than that in the case of human voice, so that the output of the low-pass filter 11 and thus the DC conversion circuit 13 is increased. . As a result, the voltage control amplifier 14 increases the output level of the pitch conversion circuit 5 and outputs it to the adder 3. That is, at this time, the bass is emphasized.

FIG. 2 shows the configuration of another embodiment of the heavy bass reproducing apparatus of the present invention.

In this embodiment, an amplifier 21 and a speaker 22 dedicated to deep bass are provided, the adder 2 is omitted, and the output of the reproducing apparatus 1 is directly supplied to the speaker 7 via the amplifier 6 and the adder is added. The output of 3 is supplied to the speaker 22 via the amplifier 21.

FIG. 3 shows the configuration of a third embodiment of the heavy bass reproducing apparatus of the present invention.

In this embodiment, the conventional apparatus shown in FIG.
A high-pass filter 31 is provided between the pitch converting circuit 5 and the amplifier 3.
Has been inserted. Other configurations are the same as those in FIG.

The cutoff frequency of the high-pass filter 31 is the amplifier 6,
It is set corresponding to the frequency characteristics of the speaker 7 and the like. For example, when the speaker 7 can reproduce up to 40 Hz, the cutoff frequency of the high pass filter 31 is set to 35 Hz. As a result, the low frequency components output from the pitch conversion circuit 5 are removed from the components of 35 Hz or less, and then supplied to the adder 3.

Therefore, it is possible to prevent the unreproducible low frequency component from being unnecessarily supplied to the speaker 7 and to prevent distortion.

FIG. 4 shows the construction of a fourth embodiment of the heavy bass reproducing apparatus of the present invention.

In this embodiment, the high pass filter 41 is inserted in the preceding stage of the pitch conversion circuit 5. Other configurations are similar to those in FIG.

In the case of this embodiment, unnecessary low frequency components are removed from the signal before being input to the pitch converting circuit 5. Therefore, when the amplifier 6 and the speaker 7 have the same characteristics as those of the embodiment of FIG. 3, the cutoff frequency of the high pass filter 41 is 70 Hz.
Is set to. As a result, if the pitch conversion circuit 5 halves the frequency of the input signal and outputs it, the signal output by the pitch conversion circuit 5 includes frequency components of 35 Hz or less, as in the case of FIG. Disappear.

FIG. 5 shows the construction of a fifth embodiment of the heavy bass reproducing apparatus of the present invention.

In the case of this embodiment, the adder 2 in the embodiment of FIG. 3 is omitted, and an amplifier 21 and a speaker 22 dedicated to deep bass are provided. Then, the output of the reproducing apparatus 1 is supplied to the speaker 7 via the amplifier 6, and the output of the adder 3 is supplied to the amplifier 21.
Is supplied to the speaker 22 via.

[Advantages of the Invention] As described above, according to the heavy bass reproducing apparatus of claim 1, the ratio of the signals generated and added by the pitch converting circuit is controlled in accordance with the frequency of the input signal. Since it is set to a low frequency component (80Hz) lower than that of a human voice, especially a male voice.
If there are many (the following components), it is judged that it is a musical sound, not a human voice, and the bass is emphasized. If there are few low-frequency components, it is judged as a human voice and the bass is not emphasized. You can Therefore, it is possible to prevent the human voice, particularly the male voice, from becoming unnatural.

[Brief description of drawings]

1 to 5 are block diagrams showing the construction of an embodiment of the heavy bass reproduction apparatus of the present invention, and FIG. 6 is a block diagram showing the construction of an example of a conventional heavy bass reproduction apparatus. 1 ... Playback device, 2, 3 ... Adder, 4, 11 ... Low-pass filter (LPF), 5 ... Pitch conversion circuit, 13 ... DC conversion circuit, 14 ... Voltage control amplifier (VCA), 31 , 41 …… High-pass filter (HPF).

Claims (1)

[Claims] 1. A first low-pass filter for separating a low-frequency component of about 150 Hz or less in an input signal, and a pitch conversion for converting an output of the first low-pass filter into a signal of about 1/2 frequency. A circuit, an adder for adding the output of the first low-pass filter and the output of the pitch conversion circuit, and a second for separating low-frequency components of approximately 80 Hz or less in the input signal.
And a control circuit for controlling the addition ratio of the output of the pitch converting circuit to the output of the first low-pass filter corresponding to the output of the second low-pass filter. Bass playback device.